1. Field of the Invention
The present invention relates to a surface mounting component, and more particularly to a surface mounting component for which a means for enhancing the bonding strength of the surface mounting component to a mounting board is provided.
2. Description of the Related Art
Surface mounting components, such as a multilayered component having a multilayer structure, are soldered to mounting boards using a known surface-mounting process. Two known surface mounting components are shown in FIGS. 6 and 7. In both of these figures, only the mounting surface of the components is shown.
In FIG. 6, a multilayered surface mounting component 1 has a mounting surface 3 on which a plurality of electrodes is formed. A ground terminal electrode 7 extends across the entire width of the mounting surface 3 (it extends to the left and right side surfaces of the mounting surface 3 as viewed in FIG. 6). Ground terminal electrode 7 also includes extensions 15, 17 and 18 which extend to the top and bottom side surface of surface mounting component 1 as viewed in FIG. 6.
In order to mount the surface mounting component 1 to a mounting board (for example, a circuit board), the central portion 5 and edge portions 16 through 19 of the ground.terminal electrode 7 are soldered to the motherboard.
As can be seen from the drawing, the ground terminal electrode 7 is formed on a relatively wide area of the mounting surface 3. However, only areas 5 and 16-19 are soldered to the circuit boards so as to limit the amount of solder which is consumed. To this end, three solder resist films 25, made from glass glaze or the like, are formed in the stippled areas so that only the central electrode portion 5 and the end electrode portions 15-19 are exposed.
While this achieves the desired result of insuring that only portions of the ground terminal electrode 7 are soldered to the circuit, it makes it necessary to carry out a process of forming the solder resist films 25 which increases the cost of the multilayered component 1. Additionally, the bonding strength of the solder resist films 25 to the ground terminal electrode 7 is relatively low. Therefore, in some.cases, deficiencies such as release of the solder resist films 25 occur.
The prior art surface.mounting component 2 of FIG. 7 is substantially similar in structure to that of the surface mounting component 1 of FIG. 6. The basic arrangement of the ground terminal electrode 8 and the signal terminals 9-11 is the same as ground electrode 7 and signal terminals 9-11 in FIG. 6. However, rather than covering portions of the ground terminal electrode 8 with solder resist films to constrict the flow of solder on the ground terminal electrode, the prior art of FIG. 2 utilizes a plurality of slits 26 formed in ground terminal electrode 8 for this purpose. However, it is very difficult for the slits 26 to completely prevent solder from flowing to adjacent portions of ground terminal electrode 8. Moreover, the printing operation by which the ground terminal electrode 8 is formed must be highly accurate to properly form the slits 26. The shape and size of the slits 26 tend to become deficient, caused by scratchy printing or blotting.
Furthermore, in both of the multilayered component 1 shown in FIG. 6 and the multilayered component 2 shown in FIG. 7, the ground terminal electrodes 7 and 8 are large. Therefore, in some cases, the ratios of the areas of the electrodes 7 and 8 to the inner conductor films formed inside of the multilayered components 1 and 2 are mismatched, which causes distortion of the multilayered components 1 and 2 during the manufacturing process.
The foregoing problem which occurs in multilayered components can also occur in other types of mounting components.
Accordingly, it is an object of the present invention to provide a surface mounting component which can solve the above-described problems.
To achieve the object, according to the present invention, there is provided a surface mounting component to be surface-mounted onto a mounting board by soldering, which includes an isolated electrode to be soldered to the mounting board and arranged on a mounting surface of the surface mounting component so as to be electrically (and preferably physically) isolated from other terminal electrodes on the mounting surface.
Preferably, the isolated electrode per se takes an asymmetrical shape, or is arranged asymmetrically with respect to the mounting surface to have a directional discriminating function.
Also preferably, the surface mounting component is a multilayered component, the multilayered component is further provided with a terminal electrode formed on a face of the multilayered component adjacent to the mounting surface, and the isolated electrode is electrically connected to the terminal electrode via a viahole conductor and an inner conductor film formed inside of the multilayered component.
The isolated electrode may be a ground terminal electrode. In this case, the isolated electrode can be also used as a ground terminal electrode, which enhances the ground performance of the surface mounting component and provides stable characteristics.
Furthermore, according to the present invention, there is provided a mounted structure of a surface mounting component including the above described surface mounting component. The bonding strength of the surface mounting component to the mounting board is enhanced, since the isolated electrode is soldered to the mounting board.